Real‐Time Monitoring and Control of Sequencing Batch Reactors for Secondary Treatment of a Poultry Processing Wastewater

Two sequencing batch reactors were operated to evaluate their efficiency for the pretreatment of a poultry processing wastewater. Although the primary goal was to evaluate the removal efficiency for oxidizable carbon as required by the National Pollutant Discharge Elimination System, this study also examined the relationship between the removal of nitrogen species and the reactor oxidation–reduction potential (ORP). On‐site, pilot‐scale units treated a postprimary treatment side stream, with 4‐hour processing cycles, four cycles per day, with no treatment on weekends. State‐of‐the‐art instrumentation for real‐time pH, ORP, and dissolved oxygen (DO) monitoring and process control based on ORP set points were used. Consistent effluent quality was achieved while treating a variable composition wastewater. By using ORP set points to control the duration of aeration, thus minimizing air blower operation time, removal efficiencies of greater than 93 and 35% were achieved for oxygen demand and ammonia, respectively. Characteristic features of the ORP profiles depicted the transition to low DO levels (≪ 1.0 mg/L). In addition, pH monitoring enhanced the usefulness of ORP readings as the means of identifying the onset of anoxic conditions and the dynamics of the nitrogen transformation processes.